The present invention generally relates to fabrication of semiconductor devices and more particularly to a fabrication process of a semiconductor device including a dicing process of a semiconductor wafer and an apparatus therefor.
In a fabrication process of semiconductor devices, a very large number of semiconductor devices are formed commonly on a single semiconductor wafer. The semiconductor wafer thus formed with the semiconductor devices are then divided into individual semiconductor chips by a dicing process that includes a sawing process conducted by a dicing saw.
In such a dicing process, it is commonly practiced to protect the semiconductor wafer, on which semiconductor devices are already formed, by an adhesive tape, such that the semiconductor devices are not damaged by the sawing process achieved by a dicing saw. The sawing may be conducted such that the depth of the dicing grooves, formed as a result of the action of dicing saw, exceeds the thickness of the semiconductor wafer (full-cut dicing), or alternatively such that the depth of the dicing grooves is smaller than the wafer thickness (semi-full-cut dicing). Further, it is practiced to use an adhesive tape carrying a UV (ultraviolet)-cure type adhesive layer on a tape base for the foregoing adhesive tape, for facilitating the removal of the tape after the semiconductor wafer is divided into individual semiconductor chips. The tape base is typically formed of a polyvinyl chloride resin or a polyolefin resin.
After such a sawing process or alternatively during the sawing process, a cleaning process is conducted for removing dust particles formed as a result of the sawing, by applying a jet of a cleaning liquid such as water. Further, a first drying process is conducted immediately after the cleaning process for eliminating the cleaning liquid by applying an air jet.
In addition to the foregoing first drying process, it has been necessary, in the conventional dicing process, to conduct a second drying process, particularly in the case of the full-cut process, for removing water from the dicing grooves. In the dicing grooves, which are formed as a result of the sawing of the semiconductor wafer by the dicing saw, it should be noted that the adhesive layer on the tape base is exposed. This second drying process is conducted in view of the fact that the UV-curing of the adhesive layer tends to become imperfect when the UV-curing of the resin is conducted under a condition in which the adhesive layer is covered by a medium that contains oxygen such as water. Thus, it has been practiced in the conventional dicing process to carry out the second drying process in a dry N2 environment for at least 30 minutes.
Thus, when a six-inch semiconductor wafer is to be divided into semiconductor chips each having a size of 5 mm×5 mm in the conventional dicing process, it takes about 5 minutes for sawing the semiconductor wafer into individual semiconductor chips, about 1 minute for the cleaning process as well as for the first drying process, about 30 minutes or more for the second drying process, about 1 minute for manually transporting the semiconductor chips from a dicing saw to an UV-curing apparatus together with the adhesive tape, and about 1 minute for curing the adhesive layer on the tape in the UV-curing apparatus. In addition, there may be an extra time needed for setting the semiconductor chips on the UV-curing apparatus in the state that the chips are held on the adhesive tape.
Thus, it will be understood that the conventional fabrication process of semiconductor devices has suffered from the problem of low throughput of production, primarily due to the existence of the second drying process in the dicing process. When the second drying process is eliminated, on the other hand, the adhesive tape remains sticky in correspondence to the part of the tape where the dicing grooves are formed, and the semiconductor chips may carry uncured, sticky adhesives thereon when the chips are picked up from the tape. When this occurs, the yield of production of the semiconductor device in the later process, such as the packaging process, may be deteriorated.